Gelatin–tricalcium phosphate membranes immobilized with NGF, BDNF, or IGF-1 for peripheral nerve repair: An in vitro and in vivo study Ming-Hong Chen, 1,2 Pei-Ru Chen, 1 Mei-Hsiu Chen, 3 Sung-Tsang Hsieh, 4,5 Feng-Huei Lin 1,6 1 Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan 2 Division of Neurosurgery, Department of Surgery, Cathay General Hospital, Taipei, Taiwan 3 Department of Internal Medicine, Far Eastern Memorial Hospital, Taipei, Taiwan 4 Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan 5 Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan 6 Department of Biomedical Engineering, National Taiwan University Hospital, NTU, Taipei, Taiwan Received 15 November 2005; revised 13 January 2006; accepted 3 March 2006 Published online 2 August 2006 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.a.30813 Abstract: In the present study, NGF, BNDF from the neurotrophin family and IGF-1 were covalently immobi- lized on gelatin–tricalcium phosphate (GTG) membrane using carbodiimide. We investigated the effects of these growth factors released from the GTG composites on cul- tured PC12 cells and sciatic nerve regeneration across a 10-mm-long gap in rats. In PC12 cell culture, the total pro- tein content and MTT assay indicated more cell attach- ment on the composites modified with growth factors. The IGF-1 group showed a higher survival promotion effect on PC12 cells than did BDNF and NGF groups. On the other hand, NGF released from the composite showed the high- est level of neuritogenesis for PC12 cells in neurite out- growth assay. In the animal study, the GTG conduits modified with various growth factors were well tolerated by the host tissue. In the regenerated nerves, the number of the axons per unit area of the BDNF group was signifi- cantly higher than that of NGF and GTG groups but simi- lar to that of IGF-1 group. However, the average axon size was the largest in NGF group. This result was in concord- ance with the neurite outgrowth assay in which NGF showed the highest neuritogenic potential. In the assess- ment of motor and sensory recovery after nerve repair, conduits modified with various neurotrophic factors showed a more favorable outcome in compound muscle action potential. The BDNF group had a better gastrocne- mic muscle weight ratio than blank GTG repair. Neverthe- less, the different effects of GTG conduits modified with various neurotrophic factors on functional recovery cannot be simply illustrated in the sciatic function index. Ó 2006 Wiley Periodicals, Inc. J Biomed Mater Res 79A: 846–857, 2006 Key words: peripheral nerve regeneration; gelatin; bio- degradable nerve conduit; glutaraldehyde; neurotrophic factor INTRODUCTION In clinical practice, when large gaps remain between the ends of injured peripheral nerve, nerve autograft- ing has been the first choice for repairing nerve gaps. However, artificial guidance channels hold promise for replacing autologous nerve grafts and offer an ‘‘off-the-shelf’’ solution to avoid the sacrifice of a healthy nerve. In addition, autografting has inevitable disadvantages such as extended surgery, loss of the donor nerve function, limited supply of donor nerves, and mismatch of diameter and fascicular organization between lesioned nerve and graft. Over the recent years, research has concentrated on the development of biodegradable artificial nerve guides. Among the wide range of natural and synthetic materials that has been developed for use as a nerve guidance channel, gelatin is one of the first materials to be tested as a nerve guide. 1 Gelatin is a biodegradable polymer with good biocompatibility, plasticity, and adhesiveness. The use of proper crosslinking agents such as glutaral- dehyde at low concentration further allows modulat- ing the mechanico-chemical properties of gelatin films. 2 We previously developed a biodegradable composite composed by tricalcium phosphate and glutaraldehyde crosslinking gelatin (GTG) with good mechanical properties feasible for surgical manipula- tion. While culturing with Schwann cells and PC12 cells, the GTG composite showed good biocompatibil- Correspondence to: F.-H. Lin; e-mail: double@ha.mc.ntu. edu.tw Ó 2006 Wiley Periodicals, Inc.